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(No Model.)

L. D. BLISS. TBLEGRAPH KEY. No. 530,082. Patented Dec. 4, 1894.

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UNITED STATES PATENT OFFICEe i LOUIS D. BLISS, OF WASHINGTON, DISTRICTOF COLUMBIA, ASSIGNOR TO CHARLES W. NEEDHAM, OF SAME PLACE.

TELEGRAPH-KEY.

SPECIFICATION forming part of Letters Patent No. 530,082, dated December4, 1894.

Application iled March 7, 1894. Serial No. 502,760. (Nomodel.)

Toa/ZZ whom it may concern: .Be it known that I, Louis D. BLISS, acitizen of the United States, residing at Washington, in the VDistrictof Columbia, have invented certain new and useful Improvements inTelegraph-Keys, of which the following is a specification.

In the use of the ordinary system of telegraphy, especially Where whatis known as the Morse key and sounder is used in transmitting andreceiving, it is a Well-known objection that unauthorized persons canread and understand the message being transmitted and received bylistening to the sounds made by the key, or by the sounder or receivingdevice, and this is especially true where a large number of instrumentsare operated together in the same room, for instance, and they areadjusted and supplied with sufficient batterypower to make distinct andloud sounding signals.

One of the objects of my present invention is to provide means wherebyan ordinary telegraphic message may be transmitted and reby authorizedpersons, but which cannot be ceived in a manner to be clearly understoodsurreptitionsly read and understood by unauthorized persons. In otherwords,I provide a practically silent transmitter or key and a receiverwhich while the sounds are distinct and sharp and of a character to beeasily readv and understood when the instrument is in the properposition, they are of such slight volume that they cannot be heard orunderstood by unauthorized persons.

In my prior application, Serial No. 487,965, tiled October 12, 1893, Ihave illustrated and described a receiving instrument specially adaptedfor this classof work, and capable of overcoming the objections stated,as far as the receiving end of the lineis concerned, and the object ofmy present invention is to provide a transmitting instrument or keywhich, while it shall conform as nearly as may be to the ordinarytransmitter keyin use, shall perform its functions practicallynoiselessly, so that the signals sent cannot be heard except by theproper person connected with the line.

Further, my invention includes the combination of such a noiselesstransmitter and re- 5o ceiving instrument, and as such an instrument isnot adapted to be used to callan operator at a station when adjusted forthis purpose, my invention further includes some sort of an arrangementwhereby `the attention of .the operator may be called to the fact that asignal is to be transmitted.

With these general statements as to the purposes and objects of myinvention, it may be considered to consist in a noiseless transmitterkey, and the combination with said key of a suitable receiver and signaldevice, substantially as hereinafter more particularly pointed out.

Referring to the accompanying drawings: Figure l, is a side view of adesk or table, showing an arrangement of devices embodying my invention.Fig. 2, is a plan view of the same; and Fig. 3, is a longitudinal,vertical section through the noiseless key, showing the preferredconstruction thereof.

The receiving table or desk is shown as comprising a platform A, and auupright A', on which the various instruments are mounted, but this ofcourse, is not essential to my invention, being shown only as aconvenient embodiment or arrangement of the parts, and of course can bevaried to suit the requirements of any particular case. Supported onthis platform is a noiseless key B, 8o and this is connected with theelectric circuit in the usual way, by conductors passing through thebase of the platform, and arranged also on the platform are thebindingposts c, to which the receiverC, is attached by means of aflexible cord C', or otherwise, and also mounted on the upright is asignal device D, which is also arranged to be operated by thetransmitting key, in the manner more particularly pointed outhereinafter.

The transmitter key B, embraces the -usual base-piece B', having ears orstandards B2, in which is mounted the key-lever B3, which is under thebias of a spring, as B4, and is provided with the usual knob or handleB5, and an adjustable back-stop B6. In other words, so far the key isvshown in the conventional form, and while I-have illustrated one of thescopes most com mon forms, of course, any other wellknown or equivalentform may be used, to suit the pleasure of the operator. It is usual toprovide the back-stop with a metallic or other rest-piece B7, whichwill. produce a sound when the back-stop comes in contact therewith, butto avoidthis objection and to aid in making the key noiseless, I providea back-rest B7, of some non-resonant or non. sound-producing material,such for instance,

control the electric current and produce a signal on the line, producesa 'loud and distinct noise, so that the signals can be easily read andunderstood by unauthorized-persons. in the vicinity of the transmitter,A In order to avoid this, I provide the key-lever with a contact b,which may be of platinum or similar material and provide another contactb', which may be of the same material, and so -support rthe contact,that when the two contacts are brought together to control Ithe electriccircuit, practically no noise sha1-l be made which would enable anunauthorized person to ascertain the nature of themessage being sent.'Vhile various means of supporting this Acontact may be used, I-havefound it desirable to have it maintained with considerable rigidity or'positiveness in its tixed or normal position, but still be capable ofyielding perhaps to a slight extent, and anyway being supported by anon-resonant or sound-transmittin g support. I have found rubber -to beone of the best materials, and the contact may be supported on a blockor mass of rubber and connected directly with the line wire e, but as arefined and more satisfactory means of supporting the contact, I connectit to a flexible conductor E, and coil the conductor between layers of arubber sheet or fabric f. Thus, I have shownthe contact b', as connectedto the end of the conductor e, and the conductor is wound preferablyin aspiral relation between the superposed layers of the rubber fabricor'sheet f,` and in this way not `only does the rubber tend manipulatedin the usual way. Not only,

does this permit the`key to operate as a noiseless key, but the somewhatelastic contacts make the manipulation of the key less tiresome t0 theoperator. l

While of course, any receiving apparatus can be operated in theusual'way with a key of this character, in order to further carry outthe main object of my invention, Ipreferably use a receiver C, which canbe of a reduced size, and in which while the sounds or signals shall besharp, clear and distinct,- so that they can bereadily heard when thereceiver is applied to the ear of the receivingoperator, they cannot beunderstood by unaut-horized persons, and I do not deem it necessaryherein to describe the specific construction'of such a device, as it isfullyset forth in my for- .mer application, and as broadly considered,

an ordinary magneto-telephone receiver mayy be used in its place.

As before intimated, it is ,desirable to bev able to call an operator atany 4particular' station lto let him know that communication is desired,and as the receiveudoes not ordinarily give out a sufiicient sound toattract the attention of the operator, some means has to be provided forcalling him. It is possible to adjust the receiver C, so that thesignals can be heard at a considerable distance from the instrument, andthereby attract the attention of the operator, but as this would requirethat the receiver should be in the transmitting circuit all the time, itwould destroy to a great exten t the purposes and objects ot' myinvention, as unauthorized persons could listen and obtain the messagespassing through the instrument destined for other stations. In ordervto-avoid all these difficulties, vI provide a calling apparatus D, andthis is shown as comprising a magnet D', which is arranged in theelectric circuit, but which is so wound'that it acts as a sluggishmagnet, and'willnot be magnetized by the ordinary currents produced insending the usual signals, and s6 that its armature D2, would not befully attracted unless there was an unusual prolongation of the' continnous current, or dwell in the operation ofthe transmitting key. As,however, such a magnet ton D4, connected by 'fa' pitman D5, to vthearmature D2, and-there is a'check valve D6, controlling 'the 4opening@Land the retracting spring D7, vis so adjusted as'to normally holdthepiston in the uppermost part of the cylinder,o\r adjacent' to the valve.When the coils of the magnet Dare energized, the tendency, of course, isiirstto attract the armature lever D2, and its armature,but it being atthis time at the greatest distance from the magnet, not only is theattraction of magnet less, but the dash-pot tends to prevent the jrapid-movement of the armature lever until after a relativelyconsiderable time, longer 'than any ordinaryzsignal to be transmitteding easily to permit the piston to rise in the cylinder. It will thus beseen that only when there is a prolongedclosure of the circuit made atthe transmitting key, so that the 5 magnetism of the magnet D', will bemainand give a distinct signal. It will thus be 'seen that with thisarrangement of circuits, not only can a message be noiselesslytransmitted by manipulating the noiseless key, but .lc it can'bereceived so that it will be unintelligible except to the proper person',and the danger of surreptitionsly obtaining knowl. edge of the messagesent is avoided. Moreover, the signal circuit is practically inop- 25.erative in the ordinary transmissionof the message, but by holding thecircuit closed at the transmitter, a signal may be given to attract theattention of the operator at any desired station, and it will further beobserved 39 that when once the piston iswithdrawn or practically so,from the cylinder, a series of short signals or calls can be givenbefore the piston has time to return to its normal position. It willthus be apparent that these in- 3 5 strumentsco-operate with each otherin producing a complete, noiseless, or as itmay be termed, secret systemof electric transmission and it can be readily applied to any existinglines, without material change, by sim- 4o ply substituting my noiselesskey and a practically noiseless sounder or relay.

I have found that the receiver will operate satisfactorily Without theinterposition of a local battery-at the receiving station, and it 45 canbe placed directly in line in place of the ordinary relay, and themagnet of the signal vdevice .can also' be included betweenthe/t'er--minals of the main line.'

Having thus described my inventio'niand 5o pointed outthe preferredembodiments thereof,.it will be evidentthat I do not limit myselfnecessarily to vthe precise construction and arrangement of parts hereinset forth, as

they may be varied in detail by those skilled in the art, withoutdeparting from the gen- 5 5 eral principles of my invention.`

What I claim" is- 1. A noiseless transmitting key, comprising a" nonresonant support, and a contact mounted on the support, substantially asde- 6o scribed.

2. A noiseless transmitting key, comprising a non-resonantcontact-support, a contact 'mounted on the support, and a non-resonantcontact-stop, substantially as described. 65

3. A noiseless transmitting key, provided Awith amen-resonantcontactsupport, comprisingsuperposed layers of fabric with a conductorinterposed between the layers, and a contact mounted on' the support,subs'tan- 7o ltially as described.

4. A noiseless transmitting key, comprising a non-resonantcontactsupport consisting 'of sup'erposed layers of fabric, a conductorspirally arranged between the superposedlayers, 7 5 and a contactmounted on th'e support 'connected to theconductor, substantially asde.- scribed.

5. The combination with an electric circuit, of a noiseless transmittingkey comprising a 8o non-resonant support and a contact mounted on thesupport, and a 'practically noiseless receiver, both the key andreceiver being" connected in said electric circuit, substantially asdescribed. 85

6. The combination with an electric circuit, of a. noise-,lesstransmitting key, comprising a non-resonant contact support and acontact mounted onY the support, a non-resonant y1 'e.- ceiver includedin the circuit, and a retard- 9o ingY signal device also included inlthe circuit, substantially as described.

i7.' The combination with an electric. circuit, of a noiselesstransmitting key, cbmprising a non-resonant contact support'and acontact 95 mounted on the support, a non-resonant receiver included inthe circuit, a magnet also included in the, circuit, an armaturelforithe.

magnet, and retarding devices connectedto the armature, substantiallyas'desoribed.-

In testimony WhereofuI. have signed my' name to this-specification inthe presenceof two subscribing witnesses. i

Louis n. Buss.

4:rco

Witnesses:

F. C. SCHOFIELD, W. S. CoLL1Ns.-

